Re: #(set-global-staff-size 40)

[Pierre Perol-Schneider]

Try :

tagline = \markup\fontsize #-5 "My Tagline"

See also :

 

http://lilypond.org/doc/v2.18/Documentation/notation/setting-the-staff-size

\score{
  …
  \layout{
    #(layout-set-staff-size 15)
  }
}

and for v2.19 : http://lilypond.org/doc/v2.19/Documentation/notation/setting-the-staff-size

\magnifyStaff

Cheers,

Pierre